Field of the Invention
The present invention relates to a technique for returning an information processing apparatus including a main system and a subsystem from a power-saving state at a high speed.
Description of the Related Art
With a growing awareness of power saving, recent information processing apparatuses have been set to enter a power-saving state more frequently than conventional information processing apparatuses. Thus, at the time of when a user attempts to use a copying machine, the copying machine is more likely to be in the power-saving state. It has therefore become more important than before to enable the copying machine to return from the power-saving state in a short time to execute a job such as copying.
On the other hand, the copying machine may include a controller including two systems, i.e., a main system and a subsystem. The main system controls a response to a user operation via an operation unit and reception of a print request via a network. The subsystem controls a scanner device and a printer device to control execution of jobs such as copying and printing.
Recently, the copying machine has restricted the supply of power to the main system and the subsystem when entering the power-saving state, in order to make power consumption during standby as low as possible to achieve the reduction of power consumption (see Japanese Patent Application Laid-Open No. 2009-223866).
In an image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2009-223866, the supply of power to a central processing unit (CPU) of the main system and a CPU of the subsystem is stopped when the image forming apparatus has shifted to the power-saving state (first power-saving mode), so that the power consumption in the power-saving state is reduced.
However, in the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2009-223866, it takes time to return from the power-saving state to a standby state. In the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2009-223866, when a factor for returning the image forming apparatus from the power-saving state has been detected, power is supplied to the CPU of the main system and the CPU of the subsystem. The CPU of the main system then executes a boot program developed in a random access memory (RAM) of the main system. Subsequently, the CPU of the main system transfers a boot program for the subsystem to a RAM of the subsystem. The CPU of the subsystem executes the boot program developed in the RAM of the subsystem. Thus, according to Japanese Patent Application Laid-Open No. 2009-223866, in a case where the image forming apparatus returns from the power-saving state, the CPU of the main system executes the boot program to perform startup processing. After that, the CPU of the subsystem executes the boot program to start startup processing. Thus, it takes time for the image forming apparatus to return from the power-saving state.